[ storage ] time . Plastic-lined carbon composite vessels , operating at 350 – 700 bar , are lighter and more suitable for transport applications , though they come with high costs due to their materials and expensive balance of plant at elevated pressures . Consequently , the high cost of pressure vessels , gas compression , and management of highpressure safety present significant challenges to the scalability of compressed gas storage .
Cryogenic liquid storage , another prevalent method , stores hydrogen at temperatures below −253 ° C , achieving a higher energy density . This method is preferred for large-scale storage and long-distance transportation , but it poses substantial safety , technical , and economic challenges . Liquefaction is energy-intensive , amounting to 40 – 50 % of the energy content of hydrogen . Liquefaction equipment is capitalintensive , requiring a project scale that may not be met by many distributed ‘ green hydrogen ’ generation projects . Furthermore , hydrogen ’ s low boiling point leads to unavoidable boil-off , resulting in continuous energy losses approaching 30 %. Safety and specialized infrastructure are also critical challenges due to risks such as leaks , frostbite , and explosion hazards . Given these complexities , cryogenic storage is typically limited to large-scale stationary industrial applications , where its high costs and infrastructure requirements pose a barrier to widespread use .
Lastly , metal hydride storage offers a way to store hydrogen by chemically bonding it with metal alloys , enabling storage at low pressures and ambient temperatures in a solid state . Despite these advantages , metal hydride systems are generally heavy and require very high amounts of heat to release hydrogen , making their operation more complex , energy-consuming , and therefore inefficient . This weight and the associated thermal management needs limit their use , confining them primarily to stationary applications or niche uses , such as in forklifts .
Thus , while metal hydride systems offer distinct advantages in specific use cases such as material handling , their limitations make them unsuitable for broader hydrogen mobility and gas transport solutions .
Reticular material-based solid-state hydrogen storage
Reticular materials such as metal-organic frameworks – invented by Omar Yaghi , Professor of Chemistry at the University of California , Berkeley , and co-founder of H2MOF – offer a promising alternative to traditional hydrogen storage technologies . Reticular materials are crystalline materials composed of metal ions or clusters coordinated with organic ligands , forming porous structures with extremely high surface areas . Nano-engineered with atomic precision , these reticular materials are ideally suited for solid-state hydrogen storage because they can trap hydrogen molecules within their pores at low pressures and near-ambient temperatures , providing significant advantages in safety , efficiency , and scalability .
How reticular materials store hydrogen
MOFs are unique in their ability to adsorb and store large amounts of hydrogen within their porous networks at low pressures . This adsorption occurs at a molecular level , where hydrogen molecules are trapped in the high surface area of the reticular material . By tuning the chemical composition and pore structure of the reticular material , it is possible to optimize hydrogen storage capacity .
• Physical adsorption : Hydrogen is stored via weak van der Waals forces within the pores of the reticular material , allowing for easy release under controlled conditions .
• Low-pressure storage : Reticular materials can store hydrogen at pressures as low as 30 bar , reducing the need for heavy and costly highpressure vessels .
Hydrogen Tech World | Issue 20 | February 2025 21